Van Grack recently left the probe to return to the agency's national security division, while Freeny will remain on until mid-October before returning to the agency's criminal division.

Carr said Van Grack will continue to contribute to the special counsel investigation "on specific pending matters that were assigned to him during his detail."

ADVERTISEMENT

The spokesman told CNN that the prosecutors' return to previous postings were not a result of disciplinary measures.

The investigation reached a new milestone last month with an agreement from Manafort to plead guilty ahead of a second trial in Washington, D.C., to numerous criminal charges surrounding his lobbying work in Ukraine and subsequent efforts to launder money through foreign bank accounts.

Manafort is set to be sentenced later this year as part of his trial in Virginia, where a jury convicted him on eight counts. Former national security adviser Michael Flynn, who pleaded guilty in 2017 to lying to the FBI about his contacts with Russian Ambassador Sergey Kislyak during the presidential transition, is also slated to be sentenced later this year.